Bit holder assembly



A ril 24, 1956 H. E. SMITH BIT HOLDER ASSEMBLY Filed June 50, 1954 32 INVENTOR.

HERMAN E. SMITH ATTORNEY United States Patent BIT HOLDER ASSEMBLY Herman E. Smith, Park Forest, 11]., assignor to Goodman Manufacturing Company, Chicago, 111., a corporation of Illinois Application June 30, 1954, Serial No. 440,465

2 Claims. (Cl. 26233) This invention relates to bit'holders for mining machines, and method of assembling the same. The principal object of the invention is to provide a simple, compact and eificient form of bit holder and method of assembly thereof, especially adapted for use along the edges of a relatively massive cutter support, in places where there is insufficient room for a bit holder of the conventional form used in kerf cutting machines.

The invention may best be understood by reference to the accompanying drawing, in which:

Figure 1 is a fragmentary side view of the outer end of a radial cutter arm of the kind used in mining machines of the boring type, to which several bit holders made in accordance with the invention are applied.

Figure 2 is a top view of the radial cutter arm shown in Figure 1.

Figure 3 is an enlarged detail section taken on line 3-3 of Figure 2.

Figure 4 is a detail section taken on line 44 of Figure 2.

Figure 5 is an enlarged detail side view of one form of holder plug removed from its socket in the cutter bracket.

Figure 6 is a plan view of the holder plug shown in Figure 5.

Figure 7 is a side view of a variant form of holder plug.

Figure 8 is a plan view of the plug shown in Figure 7.

Referring now to details of the invention shown in the drawings, the same is illustrated as applied to a cutter bracket 10 of the kind used at the outer end of a radial arm 11 forming part of a boring head of a mining machine. As usual, the cutter bracket projects forwardly from the arm 11 as the boring head is advanced toward the working face in a mine, so as to cut a circular kerf in said working face. A plurality of conventional cutter bit holders 12, 12 may be mounted as usual along the front edge of the cutter bracket, said conventional bit holders each consisting of a bit block with the usual form of elongated bit-receiving aperture in which a bit 13 is detachably secured by a set screw, further details of which need not be shown herein, as such bit blocks are well known in the art. The bits 13, 13 of said conventional bit stocks 12 project as usual at varying angles from their respective bit blocks, so as to cut a relatively wide circular kerf in advance of the cutter bracket 10.

Referring now to the novel form of bit holder of the present invention, it will be understood that in some instances it is also desirable to provide one or more cutter bits 14, 14 along the leading edge 15 of a cutter bracket 10 and projecting radially outwardly from the latter, so as to insure ample clearance for the cutter bracket in the circular kerf which is initially produced by the cutter bits 13 at the front end of said bracket. Such auxiliary bits are also advantageous in case a change in axial direction of advance of the boring may be effected in the head during cutting.

In addition, it is also advantageous to provide one or more cutter bits 16, 16 projecting from the extreme end of the radial arm, as shown in Figures 1 and 2, so as to prevent heeling of the arm when the axial direction of advance of the boring head is changed. The present invention is especially directed to a simple, compact and etficient form of cutter bit holder which is capable of being readily applied in any desired location in an exposed face of any moving cutter member, adjacent one edge thereof.

Figures 3, 5 and 6 show the construction and assembly of a cutter bit holder for the auxiliary bits 14, 14, when arranged along the leading edge 15 of the cutter bracket 10. Each of said bit holders is formed by drilling a circular bore or hole 18 in the outer face of bracket 10 of proper diameter and depth to receive a cylindrical holder plug 19 in close fitting engagement therein. The holder plug is formed with an aperture 20, extending axially therethrough, of elongated rectangular shape in transverse section of proper size to receive the shank 21 of a cutter bit 14 in endwise loose fitting engagement therein. The aperture 20 may also have opposed arcuate grooves 22 formed lengthwise along their opposite longer sides, to afford access to the bottom of the bit shank by a suitable tool, for removing the bit when necessary.

Each cylindrical plug 19 has an opening 23 extending through one side wall thereof, and communicating with one end of the bit receiving aperture 20 so as to expose a face 25 of bit shank 21 for engagement by a set screw 28 when the bit is in place in said aperture. In the preferred form shown herein, the opening 23 is formed by milling a transverse slot 24 across the side wall of the plug 19, as shown in Figures 3 and 5, of sufficient depth to intersect the bit receiving aperture 20.

The set screw 28 is threaded through the adjacent wall of the cutter bracket on an axis substantially at right angles to the axis of the plug receiving bore 18. The set screw may have a reduced inner end portion 29. When said set screw is screwed home with its inner end 29 in locking engagement against bit 14, as shown in Figure 3, said set screw also forces the cylindrical plug against the rear face of the bore 18, so as to secure both the bit and plug in place in the bracket. When the set screw is unscrewed from engagement with the bit, the reduced end of the set screw may engage the overhanging shoulder 25 of the transverse slot 24, to retain the plug loosely in the bore 18.

Figure 4 shows two variant forms of bit holding plug assemblies, the assembly at the right side of this figure being the same as that shown in Figure 3; the assembly at the left side being modified so that the set screw 30 can be engaged with a side face of a bit shank 31 instead of to the front edge of the shank. In the last mentioned variant form of assembly, the cylindrical holding plug 32, shown in detail in Figures 7 and 8, is the same form as the plug shown in Figures 5 and 6, excepting that the side aperture 33 in the plug opens into the bit receiving aperture 34 at one side of the latter. In other respects the construction and operation is the same as previously described in connection with the form shown in Figures 3, 5 and 6.

Among the advantages of the bit holding assembly disclosed herein is that it permits a bit to be secured in any desired position adjacent the edge of a cutter bracket, without requiring any conventional conformation of bit holder. All that is necessary is to drill a bore 18 in the desired place for a holder plug, and an intersecting threaded bore for a set screw. The holder plug, bit, and set screw are then assembled in the manner shown and described. A further advantage is the arrangement whereby the set screw can be partially withdrawn to release the bit, but still hold the plug in place in the bore.

Although I have shown and described a preferred form of my invention, it should be understood that the disclosure is only illustrative and should not be understood to limit or confine my invention except by the appended claims.

I claim:

1. A bit holder assembly formining machines including an elongated cutter support having a corner edge generally rectangular in cross section, said edge having a bore in one face generally parallel to the adiacent other face, a cylindrical plug adapted for fitting engagement in said bore, said plug having an elongated slot extending axially thereof for receiving the shank of a cutter bit in endwise slidable engagement therein, said cutter support edge having a threaded aperture through the adjacent side wall thereof communicating with said bore substantially at right angles thereto, said plug having an aperture through its side wall adapted to haveregistering relation 1 with the threaded aperture in said cutter support when the plug is inserted in said bore, to permit the inner end of a set screw to engage a bit in said bit-receiving aper- 4 ture in said plug to secure both said bit and plug in said bore.

2. The structure of claim 1, wherein the set screw aperture in the plug is formed by a transversely extending slot in the side wall of the plug intersecting the bit receiving aperture, and having an overhanging shoulder for engagement by the end of the set screw to retain the plug in the bore when the screw is removed from engage ment with the bit.

References Cited in the file of this patent UNITED STATES PATENTS 1,487,217 Dillon Mar.- 18, 1924 2,348,061 Doberstein May 2, 1944 2,647,737 Stephens Aug. 4, 1953 FOREIGN PATENTS 648,238 Great Britain Jan. 3, 1951 

